The present invention relates to a method of manufacturing amorphous silicon hydride film for use in an electro-photographic photoreceptor.
When producing a drum of electrophotographic photoreceptor by forming an amorphous silicon hydride (hereinafter referred to as a--Si:H) film, it is necessary to make the thickness of the film ore than 20 .mu.m in order to obtain sufficient initial voltage (generally more than 500 V). To this end it is desirable to make the deposition rate of the film large, and processes have been tried in which non diluted SiH.sub.4 at a few hundreds SCCM flow and radio frequency power up to about 1 KW, or in which disilane Si.sub.2 H.sub.6 having a large deposition rate have been utilized.
If the deposition rate is increased in the small RF power region, however, the bond of SiH.sub.2 or (SiH.sub.2).sub.n becomes increased and a plurality of traps are generated in the band gap so that light sensitivity becomes decreased and residual voltage becomes increased.
On the contrary film having a major part of the H substituent in SiH, which is suitable for a solar cell, has good photoconducting properties and a very slow deposition rate.
Since a--Si:H is under a metaequilibrium state the internal stress is very large and its kind (compressive stress or tensile stress) and its size depend on the growth conditions. If the film is made large in thickness, therefore, the film is exfoliated from the substrate.
As described above, in order to form an electrophotographic photoreceptor, and thus a photoreceptor drum by using a--Si:H, it is necessary to satisfy the following conditions simultaneously, (1) deposition rate is high, (2) photoconductivity is suitable, (3) internal stress is small.